Soy Flour & Textured Soy Protein: Nutrients, What Research Shows and Safety

Soy flour is ground soybeans (Glycine max, a legume in the pea family). Full-fat soy flour keeps the bean's oil. Defatted soy flour has most of the oil removed. Textured soy protein (also called textured vegetable protein, or TVP) is made by pushing a soy flour mix through a heated extruder so it sets into chewy pieces. [10] Soy protein concentrate is a more refined powder. People use these ingredients to add plant protein to baking, meat-style dishes and bars. This page covers soy as an ingredient in food. It keeps it apart from soy protein or isoflavone supplements, and from hype. For tofu, edamame and whole soy foods, see the linked pages.

Read this first

• Soy is a major food allergen. The FDA lists soybeans among the nine major food allergens. For trouble breathing or swelling of the face, lips or throat, call 911 (or your local emergency number). [11] [12]
• Evidence in one line: pooled trials of soy protein in place of other protein show a small drop in LDL cholesterol (about 3 to 4%). These trials did not test flour or textured protein on their own. [5]
• Food versus supplement: NCCIH separates soy foods from soy protein and isoflavone supplements, and says supplements have not been shown to lower breast cancer risk. [4]
• Thyroid tablets: a 2023 review found mostly case reports of soy affecting levothyroxine absorption and concluded any effect probably has little clinical impact. Ask your prescriber. [7]
• Pregnancy: NCCIH says soy may be unsafe in amounts greater than those commonly found in foods. [4]

What is in it (USDA values)

USDA FoodData Central (SR Legacy) lists three soy ingredients. Do not mix them up: they differ a lot in fat, fiber and sodium.

• Full-fat soy flour, raw (FDC 174273) [1]: household portion 1 cup, stirred, 84 g.
• Defatted soy flour (FDC 174275) [2]: household portion 1 cup, 105 g.
• Soy protein concentrate, produced by acid wash (FDC 174301) [3]: household portion 1 ounce, 28.35 g.

USDA has no item for textured soy protein in the data we read, so the numbers below describe the flours and the concentrate, not extruded pieces. Check the label of a textured product.

Per USDA household portion, the numbers are the 100 g values multiplied by the portion weight.

% Daily Value uses the FDA 2016 Daily Values [14]; values vary with processing and brand. A cup of flour is a large amount for most recipes; USDA also lists 1 tablespoon (5.2 g full-fat, 6.6 g defatted). The USDA concentrate item has 900 mg of sodium per 100 g, so its sodium is the one number that stands out. [3]

Plant compounds: soybeans contain isoflavones, which NCCIH describes as plant compounds similar in structure to estrogen. [4] A 2007 laboratory study of commercial soy ingredients found total isoflavones of 120 to 340 mg per 100 g in defatted and whole soy flours, 88 to 164 mg per 100 g in soy protein isolates, and 66 to 183 mg per 100 g in textured soy proteins, and found that extrusion destroyed some isoflavones. [8] Those are measurements of food chemistry, not health results.

What research says

Eaten as food vs taken as a supplement. The cholesterol trials compared soy protein with other protein, so the result describes a swap, not an add-on. [5] NCCIH notes that research has used soy protein supplements for up to 16 weeks and concentrated isoflavone extracts for up to 6 months, and that supplements are not FDA-approved before sale. [4] Observational findings show an association, not proof of cause.

How much is a normal serving

There is no official daily amount of soy flour. The USDA household portions are 1 cup of full-fat flour (84 g), 1 cup of defatted flour (105 g) and 1 ounce of soy protein concentrate (28.35 g); see the table above. [1] [2] [3] The pooled cholesterol analysis used a median of 25 g of soy protein a day. [5] This is information, not a prescription. In baking, flour is usually mixed with other flours, so you eat much less than a cup. We did not find an official portion size for textured soy protein, so read the package.

Safety, allergy and medicines

• Allergy. Soybeans are one of the nine major allergens that US labels must name. [11] MedlinePlus lists soy among common food allergies, mostly in children, and says to call 911 or your local emergency number for a serious or whole-body reaction, especially wheezing or trouble breathing. [12] Soy flour and textured protein are made from soybeans, so they are not safe for someone with soy allergy. See food allergy basics and emergency signs.
• Raw soy flour and heat. Soybeans contain trypsin inhibitors, proteins that interfere with protein digestion. A 2025 study says heat treatment is the main way to inactivate them, with industrial steaming at 110 to 130 degrees Celsius, and reports that its digestibility results came from lab tests, not people. [9] USDA labels the full-fat flour in its data "raw". We did not find a consumer safety source on eating raw soy flour, so follow the package directions.
• Thyroid tablets (levothyroxine). Mostly case reports suggest soy products may interfere with tablet absorption; the only randomized crossover study found no difference, and the authors conclude any effect seems to have little clinical impact. [7] Do not change a medicine on your own.
• MAOI antidepressants. NCCIH says soy products high in tyramine, such as tofu and soy sauce, have been linked to dangerously high blood pressure with MAOIs. [4] It does not name soy flour or textured protein. Ask a pharmacist.
• Pregnancy and breastfeeding. NCCIH says soy in amounts greater than those commonly found in foods may be unsafe in pregnancy, and little is known about larger amounts while breastfeeding. [4] See foods in pregnancy: what official bodies advise.
• Digestion. NCCIH lists bloating, constipation, diarrhea and nausea as possible side effects of soy. [4]
• Kidney disease. USDA lists 2384 mg of potassium per 100 g of defatted soy flour (51% of the Daily Value) and 674 mg of phosphorus (54%). [2] We did not read a source with soy flour advice for kidney disease. See foods, kidney disease, potassium and oxalates.
• Warfarin. USDA lists 70 mcg of vitamin K per 100 g of full-fat soy flour (58% of the Daily Value) and 4.1 mcg per 100 g of defatted flour. [1] [2] We did not read a source on soy flour and warfarin; see foods and medicine interactions.
• Not found: we found no source in what we read on soy flour and gout, or on children.

Choosing, storing and food safety

• Read the label. Soy flour may be full-fat, defatted or toasted, and textured products may contain added gluten, starch or salt. A 2023 study of a textured product used 50% defatted soy flour, 30% gluten and 20% corn starch, so a textured soy product can contain wheat gluten. [10]
• Sodium differs widely: 13 mg per 100 g in USDA full-fat flour, 900 mg per 100 g in USDA soy protein concentrate. [1] [3]
• "Soy protein" bars and powders are supplement-style products. Their make-up varies by brand and we did not review them.
• Store flour as the package says; we did not read a source on shelf life.

Related pages

• Soy foods: what the research shows
• Tofu
• Tempeh
• Natto
• Plant milks: oat, almond, soy and others
• Foods for cholesterol and heart health